Brain inflammation is characterized primarily by microglia activation (1). Several stimuli, such as ATP (2), bloodderived factors, or microbial signals (e.g. lipopolysaccharide (LPS)), induce significant morphological changes in microglial cells (3). They become undistinguishable from active macrophages and are able to migrate and proliferate at sites of neuronal injury, where they release both neurotrophic and neurotoxic factors, and inflammatory mediators, such as adhesion molecules, cytokines, and complement molecules among others (4 -6). Consequently, microglia response remains controversial because it can either be beneficial or deleterious depending on the nature, concentration, and time of exposure to the activating stimulus, and the cellular interactions of the targeted tissue. Once the triggering stimulus wanes, microglia participate in the down-modulation of the immune response and in the regulation of their own apoptosis via secretion of antiinflammatory cytokines (3).One of the outcomes of microglia activation is the production of nitric oxide (NO) from the conversion of L-arginine to L-citrulline by Ca 2ϩ -independent inducible nitric oxide synthase (iNOS) 2 (7-9). NO is produced by numerous cells, and it is of particular importance for blood flow regulation, sleepwake cycle, food intake and thermal regulation, immune system function, and neuronal transmission (10). Particularly, in the central nervous system, NO regulation presents itself as an opportunity to intervene in human health. NO can grant neuroprotection through the following mechanisms: reduction of Ca 2ϩ influx, due to S-nitrosylation of caspase 3 and NR1 and NR2 subunits of the N-methyl-D-aspartate receptors, which leads to a decrease of cell death; activation of cyclic AMP-responsive element-binding protein and Akt via stimulation of the soluble guanylate cyclase-cyclic GMP-protein kinase G pathway; and generation of biliverdin, a precursor of bilirubin, which acts as an antioxidant and antinitrosive molecule, through the induction of the activity of heme oxygenase 1 (10).However, NO can act as a pathophysiological agent because it is associated with hypertension, diabetes, and heart failure among other pathologies (8). In the central nervous system, high amounts of NO inhibit mitochondrial cytochrome oxidase in neurons, causing them to depolarize and to release glutamate and ultimately to die by excitotoxicity via N-methyl-D-aspartate receptors (11,12). NO can also react with superoxide anions and form peroxynitrite, which detains strong oxidant properties and can damage cellular components when protein nitration takes place (10).

Diabetic retinopathy is a leading cause of blindness among adults in the western countries. It has been reported that neurodegeneration may occur in diabetic retinas, but the mechanisms underlying retinal cell death are poorly understood. We found that high glucose increased the number of cells with condensed nuclei and the number of TUNELpositive cells, and caused an increase in the translocation of phosphatidylserine to the outer leaflet of the plasma membrane, indicating that high glucose induces apoptosis in cultured retinal neural cells. The activity of caspases did not increase in high glucose-treated cells, but apoptosis-inducing factor (AIF) levels decreased in the mitochondria and increased in the nucleus, indicating a translocation to the nucleus where it may cause DNA fragmentation. These results demonstrate that elevated glucose induces apoptosis in cultured retinal neural cells. The increase in apoptosis is not dependent on caspase activation, but is mediated through AIF release from the mitochondria.

Kainate-induced epilepsy has been shown to be associated with increased levels of neuropeptide Y (NPY) in the rat hippocampus. However, there is no information on how increased levels of this peptide might modulate excitation in kainateinduced epilepsy. In this work, we investigated the modulation of glutamate release by NPY receptors in hippocampal synaptosomes isolated from epileptic rats. In the acute phase of epilepsy, a transient decrease in the efficiency of NPY and selective NPY receptor agonists in inhibiting glutamate release was observed. Moreover, in the chronic epileptic hippocampus, a decrease in the efficiency of NPY and the Y 2 receptor agonist, NPY13-36, was also found. Simultaneously, we observed that the epileptic hippocampus expresses higher levels of NPY, which may account for an increased basal inhibition of glutamate release. Consistently, the blockade of Y 2 receptors increased KCl-evoked glutamate release, and there was an increase in Y 2 receptor mRNA levels 30 days after kainic acid injection, suggesting a basal effect of NPY through Y 2 receptors. Taken together, these results indicate that an increased function of the NPY modulatory system in the epileptic hippocampus may contribute to basal inhibition of glutamate release and control hyperexcitability.

The results suggest that elevated glucose may alter glutamate neurotransmission and calcium homeostasis in the retina, which may have implications for the mechanisms of vision loss in DR.

Microbial bioreporters offer excellent potentialities for the detection of the bioavailable portion of pollutants in contaminated environments, which currently cannot be easily measured. This paper describes the construction and evaluation of two microbial bioreporters designed to detect the bioavailable chromate in contaminated water samples. The developed bioreporters are based on the expression of gfp under the control of the chr promoter and the chrB regulator gene of TnOtChr determinant from Ochrobactrum tritici 5bvl1. pCHRGFP1 Escherichia coli reporter proved to be specific and sensitive, with minimum detectable concentration of 100 nM chromate and did not react with other heavy metals or chemical compounds analysed. In order to have a bioreporter able to be used under different environmental toxics, O. tritici type strain was also engineered to fluoresce in the presence of micromolar levels of chromate and showed to be as specific as the first reporter. Their applicability on environmental samples (spiked Portuguese river water) was also demonstrated using either freshly grown or cryo-preserved cells, a treatment which constitutes an operational advantage. These reporter strains can provide on-demand usability in the field and in a near future may become a powerful tool in identification of chromate-contaminated sites.

Diabetic retinopathy (DR) is the leading cause of blindness in adults. In diabetes, there is activation of microglial cells and a concomitant release of inflammatory mediators. However, it remains unclear how diabetes triggers an inflammatory response in the retina. Activation of P2 purinergic receptors by adenosine triphosphate (ATP) may contribute to the inflammatory response in the retina, insofar as it has been shown to be associated with microglial activation and cytokine release. In this work, we evaluated how high glucose, used as a model of hyperglycemia, considered the main factor in the development of DR, affects the extracellular levels of ATP in retinal cell cultures. We found that basal extracellular ATP levels were not affected by high glucose or mannitol, but the extracellular elevation of ATP, after a depolarizing stimulus, was significantly higher in retinal cells cultured in high glucose compared with control or mannitol-treated cells. The increase in the extracellular ATP was prevented by application of botulinum neurotoxin A or by removal of extracellular calcium. In addition, degradation of exogenously added ATP was significantly lower in high-glucose-treated cells. It was also observed that, in retinal cells cultured under high-glucose conditions, the changes in the intracellular calcium concentrations were greater than those in control or mannitol-treated cells. In conclusion, in this work we have shown that high glucose alters the purinergic signaling system in the retina, by increasing the exocytotic release of ATP and decreasing its extracellular degradation. The resulting high levels of extracellular ATP may lead to inflammation involved in the pathogenesis of DR.

The aim of the present review is to discuss the evidence supporting the hypothesis that inflammation and neurogenesis play an important role in temporal lobe epilepsy (TLE) and to examine whether possible strategies that involve the pharmacological manipulation of inflammation/neurogenesis can lead to the development of novel approaches for the treatment of epilepsy. Since it is not yet clear whether the neuron-glia response obtained in this pathology is a secondary effect of an aggressive inflammation or if it is somehow related to the cause of the epileptic condition, with the present review we guide the readers through the complex and ambiguous crosstalk between neuroimmunology and epilepsy.

Several evidences suggest that glutamate may be involved in retinal neurodegeneration in diabetic retinopathy (DR). For that reason, we investigated whether high glucose or diabetes affect the accumulation and the release of [(3)H]-D-aspartate, which was used as a marker of the glutamate transmitter pool. The accumulation of [(3)H]-D-aspartate did not change in cultured retinal neural cells treated with high glucose (30 mM) for 7 days. However, the release of [(3)H]-D-aspartate, evoked by 50 mM KCl, significantly increased in retinal cells exposed to high glucose. Mannitol, which was used as an osmotic control, did not cause any significant changes in both accumulation and release of [(3)H]-D-aspartate. In the retinas, 1 week after the onset of diabetes, both the accumulation and release of [(3)H]-D-aspartate were unchanged comparing to the retinas of age-matched controls. However, after 4 weeks of diabetes, the accumulation of [(3)H]-D-aspartate in diabetic retinas decreased and the release of [(3)H]-D-aspartate increased, compared to age-matched control retinas. These results suggest that high glucose and diabetes increase the evoked release of D-aspartate in the retina, which may be correlated with the hypothesis of glutamate-induced retinal neurodegeneration in DR.